Vent valve

ABSTRACT

A vent valve wherein a valve opening to be opened or closed by a valve body is provided at its one axial end, and the other end is opened for a fluid passage and concaved toward inside at its three portions, thereby the valve body being prevented from falling off. The vent valve is used for ejecting air out of the fuel passage for a vehicle fuel pump. On the valve opening side of the barrel, a step portion is provided to divide the barrel into the valve body moving portion, where the valve body moves to open or close the valve opening, and a valve body storing portion having a larger diameter than that of the valve body moving portion. On this valve body storing portion having a larger diameter, the barrel is pressed into the vent passage.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vent valve, and more particularly toa vent valve for a fuel pump which is effective for purging air out of afuel passage in a vehicle fuel pump.

2. Prior Art

Conventionally, a vehicle fuel pump is generally provided with a ventvalve for purging air out of a fuel passage in a vehicle fuel pump. Oneof such conventional vent valves is shown in FIG. 4.

As shown, this conventional vent valve 1 comprises a barrel 2 formed tobe of substantially cylindrical shape and a steel ball 3 inserted froman opening 4 into the barrel 2, this steel ball effecting as a valvebody. The steel ball 3 opens or closes a valve opening 5 of the barrel 2according to the output of fuel. That is, the vent valve 1 is placed ina vent passage branched off from the fuel passage in a manner that thevalve opening 5 is directed upward. The steel ball 3 is at a lowerposition in the barrel by its own weight, when the fuel pump is startedto operate. Thus, air is ejected out of the pump through the valveopening 5, and then, as the vent passage is filled with fuel, the steelball 3 closes the valve opening 5.

When, however, the barrel 2 is set into the vent passage, the barrel ispressed into the vent passage, and, accordingly, a closed wall at theupper portion of the barrel 2 can deform because the barrel 2 is ofsubstantially cylindrical shape. Therefore, some fuel may leak when thepump sends out the fuel, because the barrel 2 is deformed and a gap isformed between a valve seat portion 6 around the valve opening 5 and thesteel ball 3, making it impossible for the steel ball 3 to close thevalve opening 5 hermetically.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a ventvalve, wherein it is possible to prevent a valve seat portion around avalve opening from being deformed when a barrel is pressed into the ventpassage.

The vent valve according to the invention comprises a barrel to beinserted into a vent passage branched off a fluid passage, the barrelbeing of a substantially cylindrical form, and constructed such that oneend in the axial direction of the barrel constitutes a closed wall, andthe other end is open; a valve opening formed in the closed wall; and avalve body inserted into the barrel. The vent valve further comprises astep portion formed on the valve opening side of the barrel, said stepportion dividing the barrel into a valve body moving portion where thevalve body moves to close the valve opening and a valve body storingportion having a larger diameter than the valve body moving portion.

Because of this step portion, when the abovedescribed vent valve of thepresent invention is pressed into the vent passage, deformation does notextend to the valve body moving portion of the barrel even ifdeformation occurs in the valve body storing portion. Thus, sealingproperty of the valve seat portion around the valve opening is assured.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome more apparent when referred to the following descriptions givenin conjunction with the accompanying drawings, wherein like referencenumerals denote like elements, and in which:

FIG. 1 is a partially-cut elevational view showing a fuel pump employinga vent valve according to an embodiment of the invention;

FIG. 2 is an enlarged sectional view illustrating operation of the ventvalve;

FIG. 3 is a perspective view showing a barrel of the vent valve; and

FIG. 4 is an enlarged sectional view showing a prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, a vent valve according to the invention isused for a vehicle fuel pump 7, which is located on the bottom of a fueltank (not shown). The fuel pump 7 includes a motor 8, a vane pump 9,both of which are integrally connected with each other, and a housing10. In the housing 10, a fuel passage 11 on a intake side is opened atthe lower portion where the vane pump is arranged, and a fuel passage 12on an ejecting side is opened at the upper portion where the motor isarranged. Further, on the top of the housing 10, a vent passage 13 isbranched off from the ejecting side fluid passage 12 so as tocommunicate the inside and the outside of the housing 10.

According to the present embodiment, a vent valve 14 is inserted intothe vent passage 13 to open or close the vent passage 13 according tothe fuel pressure in the vent passage 13. The vent valve 14 includes abarrel 15 and a steel ball 23 as a valve body, which is inserted into abarrel 15. The barrel 15 is formed to be substantially cylindrical formsuch that one end of the barrel in the axial direction constitutes aclosed wall which can be closed by the steel ball 23, while the otherend is open. In the closed wall of the barrel 15, a valve opening 16having a smaller diameter than the steel ball 23 is providedconcentrically to the closed wall and makes the inside of the barrelcommunicate with the outside. In the other end of the barrel 15, anopening 17 with a slightly smaller diameter than the steel ball 23 isformed. That is, as shown in FIG. 3, the opening 17 side of the barrel15 is bent toward inside on three portions 18 thereof to be a shape likea three leaf clover, resulting in forming an opening 17 with a smallerdiameter than that of the steel ball 23. Thus, falling of the steel ball23 from the barrel 15 is prevented by the bent portions 18.

A step portion 19 is formed on the valve opening 16 side of the barrel15. The step portion 19 divides the barrel 15 into a valve body movingportion 20, in which the valve opening 16 can be closed, and a valvebody storing portion 21 with a larger diameter than that of the valvebody moving portion 20. The valve body moving portion 20 is constructedsuch that the valve opening 16 can be closed by the steel ball 15according to the fuel pressure.

Next, operation of the embodiment will be described.

When the barrel 15 is pressed into the vent passage 13, a part of thebarrel 15 may be deformed by the pressing force. Yet, the deformationgoes only within the valve body storing portion 21 as shown in FIG. 2.The step portion 19 prevents deformation of the wall surface definingthe valve body moving portion 20. Thus, deformation of a valve seatportion 22 around the valve opening 16, which is to be in contact withthe steel ball 23, is prevented, thereby keeping sealing property of thevalve seat portion 22.

The vent valve 14 having the foregoing construction is inserted into thevent passage 13 of the fuel pump 7 in such a manner that the valveopening 16 of the barrel 15 is directed upwardly. And, prior to startingthe fuel pump 7, no fuel contained in the fuel passage 12 is supplied tothe vent passage 13, hence, the steel ball 23 is at lowered position byits own weight, and the valve opening 16 is open.

Upon starting of the fuel pump 7, the fuel in the fuel passage 12 issupplied to the vent passage 13. Air in the fuel passage 12 and the ventpassage 13 is ejected from the valve opening 16 to the fuel tank. And,when fuel is filled in the vent passage 13, the fuel pressure causes thesteel ball 23 to go up and then to seat on the valve seat portion 22,thereby closing the valve opening 16 and inhibiting outflow of fuel fromthe vent passage 13. At this time, as the valve seat portion 22 has notbeen deformed, the steel ball 23 appropriately seats on the valve seatportion 22, resulting in positively closing the valve opening 16.

In addition, it will be easily understood that the present invention isnot limited to the foregoing embodiment. It goes without saying thatvarious variations are possible within the scope of the invention.

For example, the foregoing embodiment has been applied to a vent valveof the fuel pump, but it may be applied to any kind of vent valves forpurging air out of a fluid passage.

As set forth above, the present invention includes a step portion formedon a barrel. Hence, it can prevent deformation of the barrel near avalve seat portion when the barrel is pressed into a vent passage, thus,the valve body positively closes a valve opening.

What is claimed is:
 1. A vent valve comprising:a barrel, formed to be ofsubstantially cylindrical form, one axial end of which constitutes aclosed wall, and the other axial end of which is open, said barrel beinginserted into a vent passage branched off from a liquid passage; a valveopening formed on the closed wall; a valve body inserted into saidbarrel; and a step portion provided on the outer periphery of saidbarrel on the valve opening side of said barrel, said step portiondividing the barrel into a smaller diameter portion and a largerdiameter portion, said barrel being inserted into said vent passage bypressing the larger diameter portion of the barrel into the ventpassage.
 2. The vent valve as set forth in claim 1, wherein:said valvebody is a sphere for opening or closing said valve opening in a mannerto come into contact with or be isolated from a valve seat portion ofthe valve opening; and, said other axial end of said barrel has anopening, measurement which is smaller than a diameter of said sphere. 3.The vent valve as set forth in claim 2, wherein:said opening is formedsuch that three portions of said cylindrical barrel are so concavetoward the inside of the barrel wherein measurement of the opening issmaller than the diameter of said sphere.
 4. The vent valve as set forthin claim 1, wherein:said vent passage is a vent passage for a fuel pumpand openly provided on one end of a housing of a vehicle fuel pump, saidvent passage being branched off from an ejecting side fuel passage assaid fluid passage.
 5. The vent valve as set forth in claim 4,wherein:said one end of said housing is openly provided with saidejecting side fuel passage; and, the other end of the housing is openlyprovided with an intake side fuel passage.
 6. The vent valve as setforth in claim 5, wherein:said one end of said housing is provided witha motor; and, the other end of said housing is provided with a vanepump.
 7. A vent valve as set forth in claim 1, wherein an inside of thebarrel is divided into a valve body moving portion where said valve bodymoves to close said valve opening, and a valve body storing portionhaving a larger diameter than the valve body moving portion.